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Finding the Fourth Proportional to 78.51, 118.38 and 66.63

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Solution

The fourth proportional to 78.51, 118.38 and 66.63 is: 100.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.51 : 118.38 = 66.63 : x
  2. Step 2: Convert to fraction form
    78.51/118.38 = 66.63/x
  3. Step 3: Cross multiply
    78.51x = 118.38 × 66.63
  4. Step 4: Simplify right side
    78.51x = 7,887.66
  5. Step 5: Solve for x
    x = 7,887.66/78.51
  6. Step 6: Final answer
    x = 100.47

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.